Do you have another 15 clone, besides the Johnson Ruffler? Can you use regular presser feet on the Ruffler?
You might want to check out the following links regarding puzzle boxes:
http://needlebar.org/main/puzzles/index.html
Singer style box: which one do I have?
http://www.victoriansweatshop.com/post/singer-puzzle-box-info-7974353?&trail=50
Pay particular attention to any by Macybaby, who started the one on victoriansweatshop
Since the 128, 221 and 15 clone are all low shank feet, you would be able to use the feet on any of them. There is a better narrow hemmer for the 221 and 15 clone. I don't remember which one it is. The narrow hemmer will work on all of them, but I think that the stitching is closer to the fold and more in the middle depending which machine you use.
Janey - Neat people never make the exciting discoveries I do.